NOt sure about the gateway, There were a quite a few products a year or so ago but most of them went belly up...
An ITG card will run you around 6-8K just for the Card. You need a lot more then the card to get it working...i.e. OTM, RLs 25.30+, Proper Packages in Switch, Cables, Ethernet Switch..and plenty of Man and troubleshooting hours to get it to work.
also, I was referring to the ITG Trunk Card above...there is also a Line side as well.
To have all the proper hardware will run you about 12-15K, that does not include any upgrades that may be needed, but your in luck, get with your vendor, if you upgrade to Release 25.40 you get all that stuff free. Doesn't mean it's free to install it or configure it, just the hardware is free. You may need to order addtional packages and such to get it to work properly but you have a choice of the ITG line or ITG trunk.
Good Luck